Investigation of the Al-adhesive transfer mechanism on Ti6Al4V blade tips under high-speed rubbing in an aero-turbine engine

Anti-adhesion Mechanism of TiB2-Deposited Ti6Al4V Blade Tip Against Al-hBN Seal Coating During High-Speed Rubbing

“…The tribology test simulating the high-speed condition of the aero-engine was carried out on a high-speed rubbing test rig. The experimental details and procedure were introduced in the previous work [7]. Figure 1 shows the schematic diagram of the high-speed rubbing test rig.…”

“…Its microstructure of the interface reaction interlayer was different from the Al-adhesive Ti6Al4V bare blade tip. The previous research [7] showed that the Al-hBN seal coating was rst smeared on the Ti6Al4V bare blade tip, and then the Ti-Al interface reaction occurred under the high friction heat during highspeed rubbing. There is a gradient Ti-Al interface reaction interlayer consisting of TiAl 3 and γ-TiAl phase with a thickness of 1.0 ~ 1.8 µm.…”

“…The frictional ash temperature of the rubbing surface is extremely high due to the cutting and rubbing between the blade tip and seal coating with a linear speed as high as hundreds of meters per second [39]. The high-speed rubbing is an intermittent interaction process, during which the Al-adhesive blade tip surfers both the rubbing heating and idling cooling cycles [7]. When the temperature changes, the difference in thermal expansion coe cient and elastic modulus between the Al-adhesive transfer layer, interface reaction interlayer and TiB 2 coating or Ti6Al4V blade tip will produce thermal stress at their interfaces.…”

“…As the results in the previous research [7], the Ti-Al interface reaction on the Al-adhesive Ti6Al4V bare blade tip, was carried out in two steps. First, the TiAl 3 phase is formed.…”

“…The present researches mainly focus on the effect of the high-speed rubbing parameters on the tribology behavior [5,6].The high linear speed and the lower incursion rate of the Ti6Al4V blade tip will intensify the Al-adhesive transfer from the Al-hBN seal coating [3]. In our previous works, it was found that the reason for the serious Al-adhesive transfer is related to the forming of a thick Ti-Al interface reaction interlayer between the Ti6Al4V blade tip and Al-adhesive transfer layer [7]. Thus, the surface modi cation of the Ti6Al4V blade tips will be an effective method to inhibit the Al-adhesive transfer during the high-speed rubbing without changing the original materials design of the seal coating or blade.…”